package com.hualidianping.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hualidianping.dto.Result;
import com.hualidianping.entity.Shop;
import com.hualidianping.mapper.ShopMapper;
import com.hualidianping.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hualidianping.utils.RedisData;
import com.hualidianping.utils.SystemConstants;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hualidianping.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result queryById(Long id) {
        //解决缓存穿透
//        Shop shop = queryWithPassThrough(id);
        //互斥锁解决缓存击穿
        Shop shop=queryWithMutex(id);
        //逻辑过期解决缓存击穿
//        Shop shop=queryWithLogicalExpire(id);
        if(shop==null){
            return Result.fail("店铺不存在！");
        }
        return Result.ok(shop);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id=shop.getId();
        if(id==null){
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if(x==null||y==null){
            Page<Shop> page = query().eq("type_id", typeId).page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            return Result.ok(page.getRecords());
        }
        //计算分页参数
        int from=(current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        int end=current*SystemConstants.DEFAULT_PAGE_SIZE;
        String key=SHOP_GEO_KEY+typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeCoordinates().limit(end)
        );
        if(results==null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        //截取from到end的部分
        List<Long> ids= new ArrayList<>(list.size());
        HashMap<String, Distance> distanceMap = new HashMap<>(list.size());
        //bug
        //跳过了所有item，导致result为null，应该提前结束
        if(list.size()<=from){
            //没有下一页了,结束
            return Result.ok(Collections.emptyList());
        }
        list.stream().skip(from).forEach(result->{
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        String idStr=StrUtil.join(",",ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);
    public Shop queryWithLogicalExpire(Long id){
        //1.从redis查询商铺缓存
        String key=CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在：null或空串都认为不存在
        if(StrUtil.isBlank(shopJson)){
            //3.不存在直接返回
            return null;
        }
        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())){
            //5.1未过期，直接返回店铺信息
            return shop;
        }
        //5.2已过期，需要缓存重建
        //6.缓存重建
        //6.1获取互斥锁
        String localKey=LOCK_SHOP_KEY+id;
        boolean isLock=tryLock(localKey);
        //6.2判断是否获取锁成功
        if(isLock){

            //4.35 注意获取锁成功应该再次检测redis缓存是否过期，做DoubleCheck，如果存在无需重建缓存。
            shopJson = stringRedisTemplate.opsForValue().get(key);
            //4.命中，需要先把json反序列化为对象
            redisData = JSONUtil.toBean(shopJson, RedisData.class);
            shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
            expireTime = redisData.getExpireTime();
            //5.判断是否过期
            if(expireTime.isAfter(LocalDateTime.now())){
                //5.1未过期，直接返回店铺信息
                return shop;
            }

            //6.3成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    //重建缓存
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    unlock(localKey);
                }

            });
        }
        //6.4返回过期的商铺信息
        return shop;
    }

    public Shop queryWithPassThrough(Long id){
        //1.从redis查询商铺缓存
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否为空
        if(StrUtil.isNotBlank(shopJson)){
            //3.不为空直接返回
            log.debug("从redis查询到商铺：{}",shopJson);
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //3.5存在但为空，返回错误
        if(shopJson!=null){
            return null;
        }
        //4.redis不存在则根据id查询数据库
        Shop shop = getById(id);
        //5.数据库中不存在则返回错误，将空值写入redis防止缓存穿透
        if(shop==null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.SECONDS);
            return null;
        }
        //6.存在，写入redis
        log.debug("从数据库查询到商铺：{}",shop);
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop));
        stringRedisTemplate.expire(key,CACHE_SHOP_TTL,TimeUnit.MINUTES);
        //7.返回
        return shop;
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    public Shop queryWithMutex(Long id){
        //1.从redis查询商铺缓存
        String key=CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)){
            //3.存在直接返回
            log.debug("从redis查询到商铺:{}", shopJson);
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断命中的是否是空值
        if(shopJson!=null){
            //返回错误
            return null;
        }
        //4.实现缓存重建
        String lockKey="lock:shop:"+id;
        Shop shop=null;
        //4.1获取互斥锁
        try{
            Thread.sleep(5);
            boolean isLock=tryLock(lockKey);
            //4.2判断是否获取成功
            if(!isLock){
                //4.3失败，则休眠重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.35 doublecheck：注意获取锁成功应该再次检测redis缓存是否存在，做DoubleCheck，如果存在无需重建缓存。
            shopJson = stringRedisTemplate.opsForValue().get(key);
            //2.判断是否存在
            if(StrUtil.isNotBlank(shopJson)){
                //3.存在直接返回
                log.debug("从redis查询到商铺:{}", shopJson);
                shop = JSONUtil.toBean(shopJson, Shop.class);
                return shop;
            }
            //判断命中的是否是空值
            if(shopJson!=null){
                //返回错误
                return null;
            }
            //4.4成功，根据id查询数据库
            shop=getById(id);
            //模拟重建的延时
            Thread.sleep(200);
            //5.不存在返回错误
            if(shop==null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            //6.存在，写入redis
            log.debug("============重建从数据库查询到商铺:{}", shop);
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL,TimeUnit.MINUTES);
        }catch (Exception e){
            throw new RuntimeException(e);
        }finally {
            //7.释放互斥锁
            unlock(lockKey);
        }

        //8.返回
        return shop;
    }

    /**
     * 将店铺存到redis中并封装逻辑时间
     * @param id 店铺id
     * @param expireSeconds 持续时间
     * @throws InterruptedException
     */
    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop=getById(id);
        Thread.sleep(200);
        //2.封装逻辑时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }
}
